1. Field of the Invention
The present invention relates to a method of preparing an InSb thin film, which is applied to a magnetic resistive element, a Hall element or the like.
2. Description of the Background Art
In general, an InSb compound semiconductor is employed as a material for a Hall element or a magnetic resistive element due to its high Hall mobility .mu.. A magnetic sensor such as the Hall element or the magnetic resistive element must have resistance of several hundred .OMEGA. to several k.OMEGA. in order to improve consistency with a sensor signal processing circuit. However, InSb is a material which has low resistivity of 10.sup.-8 .OMEGA..multidot.cm order in essence. When InSb is applied to a Hall element or a magnetic resistive element, therefore, it is necessary to form a thin film. Such formation of a thin film is also required in order to easily form a fine pattern.
In general, an InSb thin film having high mobility is formed on a mica substrate by vacuum evaporation or the like. It is empirically known that mica is the optimum material for a base material for forming a thin film of InSb. While the reason therefor is not yet clarified in detail, it is conceivable that a thin film having small reduction of mobility is formed due to excellent crystallinity of the InSb thin film which is formed on such a mica substrate.
However, it is difficult to work a final element on a mica substrate, which has cleavage in crystal structure. In general, therefore, it is necessary to temporarily form an InSb thin film on mica and transfer this InSb thin film onto a target base material for patterning the same into a prescribed shape.
An InSb film which is formed on a general substrate such as an Si substrate having an SiO.sub.2 film, an Si substrate having a film of silicon nitrides, an Si substrate having an Al.sub.2 O.sub.3 film, a glass substrate, a ferrite substrate, an Si substrate of each crystal plane orientation or a GaAs substrate exhibits mobility of about 10000 to 20000 cm.sup.2 /V.multidot.sec. Therefore, a magnetic resistive element, a Hall element or an infrared detection element which is prepared from such a film is inferior in rate of magnetic resistance change, product sensitivity and photoelectromotive force.